A conceptual framework is presented that describes the interrelations amoung psychophysical power law exponents, Weber constants for intensity, and range of sensitivity to stimulus intensity (dynamic range). Studies of odor strength, apparent effort in handgrip, and loudness discrimination under masking have been performed, and the results thus far appear consistent with the theory. A five-year program with the following goals is proposed: 1) a review of the literature on dynamic range for sensory systems; 2) investigation of a new empirical approach to the measurement of dynamic range; 3) studies to determine the effects of exercise and fatigue on psychophysical matching functions involving apparent effort of muscular contraction; 4) studies of odor strength designed to a) extend previous work on the effects of sniff intensity and b) obtain reliable estimates of both exponents and dynamic range with modern stimulation techniques; 5) studies of resolving power for loudness under masking and heaviness under parametric variation of volume, designed to determine intramodal effects of exponent change on differential sensitivity; 6) theoretical and empirical studies of range effects in psychophysical scaling and individual variation in power law exponents.